The present invention relates to the field of orthodontics, in particular a computerized system and method for identifying and correcting tooth-size discrepancies, and determining a recommended arch size predicated on a patient""s cranial-facial morphology and tooth size.
In the field of orthodontics, a mathematical ratio exists between the size (mesiodistal width) of the upper (maxillary) and lower (mandibular) teeth. This mathematical ratio should exist in an ideal dental occlusion. More often than not, and particularly in patients with orthodontic problems, a tooth-size discrepancy exists. Although there are no reliable epidemiological studies confirming these statistics, it is estimated that approximately one-third of the American public have tooth sizes that are proportional and within a reasonable range of an ideal occlusion. The remaining two-thirds of the American public, however, have teeth where the mathematical ratio is not ideal and there exists a modest to severe tooth-size discrepancy or incompatibility.
In a scientific research paper entitled xe2x80x9cDisharmony in Tooth Size and Its Relation to the Analysis and Treatment of Malocclusionxe2x80x9d by Dr. Wayne A. Bolton, a method is described for identifying the presence and magnitude of a tooth-size discrepancy (the xe2x80x9cBolton Analysisxe2x80x9d). This method may be performed on the six anterior teeth (two canines, two laterals, and two central incisors) or on twelve teeth (the six anterior teeth, the four premolar teeth, and the two first molar teeth). The mathematical ratio is compared to the ideal mathematical ratio, which is 0.772 for the six anterior teeth, and 0.913 for the twelve teeth analysis. This comparison identifies any existing tooth-size discrepancy and the magnitude of the tooth-size discrepancy, which is the difference between the mathematical ratio and the ideal mathematical ratio.
Typically, the Bolton Analysis is performed using the tables provided in Bolton""s paper, a slide rule, which is no longer manufactured, or a calculator. Therefore, determining the existence of a tooth-size discrepancy using the Bolton Analysis can be very tedious and time consuming. While the Bolton Analysis determines the existence and the magnitude of a tooth-size discrepancy, it does not quantify the mathematical correction necessary in the maxillary and/or mandibular teeth to achieve an ideal occlusion. Thus, there exists a need for a computerized system that measures teeth and accurately determines the existence and magnitude of a tooth-size discrepancy in an easy and expeditious manner.
The failure of an orthodontist to recognize the existence and amount of the tooth-size discrepancy during diagnosis, and to attain a close to ideal ratio of tooth structure during treatment, may result in treatment problems, such as crowding or spacing of the maxillary and/or mandibular teeth. Deviations from the ideal ratio may also result in a relapse of treatment and/or functional, aesthetic and health problems.
A problem arises, however, when the orthodontist attempts to correct the tooth-size discrepancy determined using the Bolton Analysis. Since the results of the Bolton Analysis are directly related to a ratio, the results do not accurately address the amount of actual anatomical correction necessary in either the maxillary or mandibular arch. As soon as a change is undertaken in any direction, the ratio changes. An orthodontist assuming that a tooth-size discrepancy can be corrected merely by adding to or removing the amount of tooth structure indicated by the results of the Bolton Analysis, in either the maxillary or mandibular arch, will err. Moreover, the results of the Bolton Analysis do not clearly demonstrate to the orthodontist or researcher the actual tooth or teeth prompting the tooth-size discrepancy. Thus, there exists a further need for a computerized system that determines the amount of anatomical correction necessary using the results of the Bolton Analysis. It would be desirable if this system would illustrate, on a monitor and/or in a printer output, the actual and average size of each tooth so that it is immediately apparent to the doctor the tooth or teeth that may be responsible for the tooth-size discrepancy.
Preformed arch wires such as super-elastic preformed arch wires are frequently used during the first and second phases of treatment to level, align, torque, and/or shape the teeth and the arches. Current orthodontic use of preformed arch wires (one for the maxillary arch, one for the mandibular arch) means that approximately 17% of patients are treated with an arch wire that is too large and 17% of patients are treated with an arch wire that is too small. Since these preformed arch wires are not adjustable to the patient""s facial size, they may create problems by over expansion or constriction of the maxillary and/or mandibular arch. These problems might be corrected later in treatment, when it is least desired, and would extend the treatment time. In addition, the use of these preformed wires may also result in xe2x80x9cround tripping,xe2x80x9d i.e., moving the teeth in the wrong direction and then having to recorrect the teeth. Thus, there exists a further need for a computerized system that determines the ideal arch wire size to effectuate a more precise and stable treatment.
The computerized system according to an example embodiment of the present invention determines the existence and magnitude of a tooth-size discrepancy, the necessary anatomical correction, the identity of the individual tooth or teeth responsible for the tooth-size discrepancy and the recommended arch wire size to effectuate treatment of the tooth-size discrepancy. The computerized system includes a computer with various input/output devices that include a computerized caliper. The computer executes a program that performs an analysis and outputs (1) the sums of the maxillary and mandibular arches, (2) the necessary anatomical correction, (3) the individual tooth or teeth responsible for the tooth-size discrepancy and (4) the recommended arch wire size. The computerized caliper is used to measure the mesiodistal width of each tooth. The computerized caliper directly inputs each tooth-size measurement into the computer.
Once the user has inputted the individual measurements for the teeth involved in the analysis, the user may compare the measurements with the average measurement for each tooth via a monitor and/or a printer output.
Using the inputted information, the program determines the magnitude of the tooth size discrepancy, the necessary anatomical correction and the recommended arch wire size. Once the tooth-size discrepancy is determined, the user may utilize the necessary anatomical correction along with a comparison of the measurements to the average sizes to determine the proper diagnosis, i.e., how much correction to make in the maxillary teeth, the mandibular teeth or a combination of the two.
The method according to the example embodiment of the present invention uses the selected arch wires during the entire course of treatment. The arch wires are selected on the basis of the tooth-size measurements of the patient.
In other embodiments, the constants used to calculate the tooth-size discrepancy, anatomical correction necessary, and the arch wire size are adjusted for the statistical differences based on race.